In one Science class of 120 pupils, 0.1 of the boys and
34 of the girls passed the exam. A total of 38 pupils passed the exam. How many boys failed the Science exam?
| |
Boys |
Girls |
Total |
| Passed the test |
1 u |
3 p |
38 |
| Failed the test |
9 u |
1 p |
82 |
| Total |
10 u |
4 p |
120 |
0.1 of the boys =
110 of the boys
Total number of boys = 10 u
Total number of girls = 4 p
1 u + 3 p = 38 --- (1)
9 u + 1 p = 120 - 38
9 u + 1 p = 82 --- (2)
Make u the same.
(1)
x99 u + 27 p = 342 --- (3)
(3) - (2)
27 p - 1 p = 342 - 82
26 p = 260
1 p = 260 ÷ 26 = 10
From (2)
Number of boys who failed
= 82 - 1 p
= 82 - 10
= 72
Answer(s): 72
